Stopping device for electric lifts



Feb. 26, 1929.

J. MAIR STOPPING DEVICE FOR ELECTRIC LIFTS Filed Dec. 16, 1926 4 Sheets-Sheet HI!Illllllllll'llllllllIlull-llillllllll 4 Sheets-Sheet J. MAIR STOPPING DEVICE FOR ELECTRIC LIFTS Filed Dec. 16, 1926 Feb. 26, 1929.

Feb. 26, 1929. 1,703,743

7 J. MAIR 4 STOPPING DEVICE FOR ELECTRIC LIFTS Filed Dec. 16, 1926. 4 Sheets-Sheet 5 a \l 859 ill I b x @f k m //V}/E/V7'0,

James flf FEB. 26, 1 929.

J. MAIR STOPPING DEVICE FOR ELECTRIC LIFTS iiled Dec. 16. 1926 4 Sheets-Sheet flmas J74 (if Patented Feb. 26, 1929.

UNITED STATES PATENT OFFICE.

JAMES MAIR, OF NEWCASTLE-UPON-TYNE, ENGLAND.

STOPPING DEVICE FOR ELECTRIC LIFTS.

Application filed December 16, 1926, Serial No. 155,315, and in Great Britain May 14, 1926.

This invention has reference to improvements in and relating to stopping devices for elect ic lifts, of the type wherein the stopic lii't is effected by the use oi a cam 1' equivalent on the cage adapted to 'rikc or bpcratc a sudtching device suitably positioned in the lift well or shaft The cage is allowed a certain estimated stoppingdistance in which to come to after the cam board has struck its switch. The actual stopping distance of the cage, however, is largely dependent upon the momentum of the loaded cage, which momentum is governed by the load in the cage. Hence the estimated stopping distance is equal to the actual stopping distance for one particular load only. A heavily loaded cage, for or:- ample, stops below the floor level, since the momentum is greater and thereby permits the cage to coast a greater distance than it would with a light load, were the current turned oii" at the same time in both instances due to the fact that in the usual elevator installation, the counter-weights are made equal in weight to the weight of the car plus of its rated load.

The object of my invention is to provide a mechanical device which automatically adjusts the position of the cam board or the equivalent with respect to the switches in the lift shatt with which the cam board co-opcrates, according to the load carried by the :age. Means to prevent the starting of an overloaded cage are provided. The device in accordance with my invention is so arranged that the cam board oi? a cage when heavily loaded strikes its floor switch sooner when descending and later when ascending then it would it lightly loaded, that is, the estimated. stopping distance is automatically adjusted to agree with the actual stopping distance necessitated by the variation in the load carried. The cage therefore stops accurately where required irrespective of the load therein.

Broadly, according to the said invention, the cam board is vertically adjustable on the cage, the adjustment being automatically effected by means influenced by the variation of load.

In order that the invention may be readily understood reference is directed to the ac companying sheet of drawings, wherein Figure 1 IS a trontview of the device in accordance with this invention; and,

Figure 2 is an end view thereof, looking in the direction of arrow A, Figure 1.

Figure 3 is a, front view of a modified form of mechanism; and,

Figure 4; is a side view thcreo't', looking in the direct at right an glee to Figure 3.

l igures and 7 are front elevation, plan an d end Kiev-i, i aci' 'oly, of a modification.

retiring to the drawings, the cage 4 is supported by a rope 7), anchored at c. The rope 7) is deflected by the pressure pin (Z on the crank arm 6, pivoted at 7, the pressure upon the rope being maintained by a spring 9, so that the lighter the load in the cage the greater the deflection of the rope. As the load increases, the rope Z) tends to straighten and in so doing rotatesthe crank arm 0 about its pivot f. This movement is transmitted to another arm h which in turn vertically adjusts the cam board 7', through suitable linkage 70. The cam board is preferably slidably mounted in a guidcway Z.

A pointer m may be provided, the movement or" which is an indication of the load in the cage (4. The pointer m may therefore directly indicate the load of the cage contents upon a dial or plate a, or, if preferred, the movement of the pointer or may be trans mitted by suitable controls p to an indicator (not shown) within the cage.

The dotted outline in Figure 1 indicates the position of the mechanism. and the cam board when the ca e is fully loaded. appreciable 'increas, in the load beyond the normal :tull load causes the arm a to drop still lower until it comes into contact with the spring-controlled plungjjer Depression of the plunger 2" forces the bridge member s away from the contacts t, t, which are in the control circuit of the lift. In this way an overloaded cage automatically cuts oli' the power necessary for starting and travelling, so that until the load in the cage is reduced, it is impossible for the cage to move. Any other cut-out switch may be operated by the arm A.

Figures 3 and l illustrate a modified form of operating mechanism, especially, but not exclusively, applicable for use with cages supported by a pliurality 0t ropes or cables. Under the action of the spring 9 the rocker arm a, rotating about the pivot f, bears against a peg or projection o upon a separately pivoted pressure member (Z pivoted at substantially right angles to the rope b there- Any by forcibly deflecting the same. As the ropes 5 tend to stireighteii under the increase elf load in the cage, the pressure member (Z moves the rocker arm it Which, through linkage 70, including a bellcrenl; 10, operates the ce rl board as and for the purposes previously dc scribed. The peg or projection Q) of the pres: sure member d may be vertically adjustable.

Lead recerding means and an ererleed stopping device are not shoivn in Figures 3 and l,

Referring to Figures 5 to i", a springpcentrolled rod 1, Which may be com ected at 013 e end to the ce n board yin. suitable interrre diary linke- 'c, is pivot-ally cenriec t other end with a rocker or cr-e l- I which in turn is pivctally nc hted er; a bracket 3 secured to the top Leer-4i l cl cage. To the bridge-like pectic; 5 ct c crenlzed member 2 is utteched en zzdjusleble bearing member 6 adapted to receive the upper extremity of a, pointed pressure pin The lower extremity of the pointed pressure pin 7 rests in a recess in siiether beeririe' 8 which spans a pair or levers l0, piyeted at 1. A pulley or rcller carrier 12 posi ioned above and pivo e ly .cenim ei l t the ve 0, connection being made between the pivot pin. r1 and I 7 Din 8 at a position s htlist a slight up n n d mevem e t 1 the cerrierlg produces a relatively large upward eyemeiit of the bearing: pin 8 and consequently er the pressure pin 7. The hoishng cables 13 pass down between and under the pairs oi pulleys lers 4, th n m e i e l s r h e to left being equal in number so that their respective forces ere balanced and neutrelized. The cables are zu chered i gi iy suitable known manner. 7 i

cage, in combination W to the top beam 4 of the cage. Th upward movement the carrier 12 tilts the lever 10, causing the pressure pin 7 to swing the era mem er about its cranked member 2 is thereby ate the red 1 against the so that by memes or suite board is le-Wered. The spi- 1 re-set-s the mechanism 1; c reuse d l1 claim: 1. A stopping: device for th type crepla e cum be l le lleer limit well-operating l9 cage, in combine. an I cable the el'er care bear-cl mechanical hected W11 e said cable and means for Y l' deflecting the cable out of a stra ject to the ariations of leads 7, whereby said cam bearer will be autmr .ticelly adjusted fer the puipeses specifier 2. A stopping device for electric l the type employing a cerboard or floor limit sivitcl'i operetmg (levicc on the e heist ng 1 lll-eCllfilllillll-V cable therefcrr, a care be CORHGtQd W th s cable, end resiliently t siohed recalls forcibly dcfiecthrg the' Cfiljl out of a straight line subject to the verim tiens of loads inseid cage whereby l board Will be autemeticelly adjusted purposes specified.

In testimony whereof I have aflixed my signature hereto this 28rd day of November, 1926." i I JAMES Mim 

